KR100547893B1 - Method and apparatus for controlling power of reverse channel in mobile communication system - Google Patents

Abstract

The present invention relates to a method and apparatus for controlling the transmission power of a reverse channel quality indication channel in a mobile communication system. In the base station according to the present invention, the control detector measures the received power of the reverse channel quality indication channel every time slot to determine whether to remove or not, and the removal rate calculator accumulates and stores the removal decision result for a predetermined N slots. The removal rate during the slot is calculated, and the control bit generator determines the power ratio control bit transmitted to the terminal according to the removal rate to indicate the increase or decrease of the power ratio relative to the reverse pilot of the channel quality indication channel. In the terminal according to the present invention, the control bit detector determines whether the control bit received from the base station is a power ratio control bit or a power control bit every time slot, and the power ratio controller determines the power ratio when the control bit is a power ratio control bit. According to a control bit, the power ratio of the reverse pilot of the channel quality indication channel is controlled, and the gain controller controls the transmission gains of the reverse channels according to the power control bit and the power ratio if the control bit is a power control bit. Thus, the present invention further improves the reliability of the reverse channel quality indication channel.

CQICH, PICH, erasure rate, power ratio, PCB, ratio control bit

Description

METHOD AND APPARATUS FOR POWER CONTROL OF REVERSE CHANNELS IN MOBILE COMMUNICATION SYSTEM}

1 is a view showing channels related to reverse power control in a mobile communication system according to the prior art.

2 is a diagram illustrating a receiver structure of a channel quality indication channel in a mobile communication system according to the related art.

3 is a diagram illustrating transmission of a power control bit and a power ratio control bit for reverse power control in a mobile communication system according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a procedure for a base station to transmit a power ratio control bit when a terminal is in soft handoff (SHO) in a mobile communication system according to an embodiment of the present invention.

FIG. 5 illustrates a procedure for controlling a transmission power of a channel quality indication channel by a terminal in soft handoff (SHO) receiving a power ratio control bit in a mobile communication system according to an embodiment of the present invention.

6 is a diagram illustrating a receiver structure of a base station for controlling a transmission power of a channel quality indication channel in a mobile communication system according to an embodiment of the present invention.

7 is a diagram illustrating a receiver structure of a terminal for controlling a transmission power of a channel quality indication channel in a mobile communication system according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating an operation in which one base station distributes power ratio control bits for a plurality of terminals and transmits them.

9 is a diagram illustrating an operation of repeatedly transmitting a power ratio control bit according to an embodiment of the present invention.

The present invention relates to a mobile communication system, and more particularly, to a method and apparatus for controlling transmission power of a reverse channel quality indicator channel (CQICH).

A typical mobile communication system, for example, a code division multiple access (CDMA) mobile communication system such as IS-2000, supports voice service only. However, as communication technology has developed along with user demands, mobile communication systems have also been developed to support data services. For example, HDR (High Data Rate) is a mobile communication system proposed to support only high speed data services.

Such a mobile communication system is considered to support only a voice service or only a data service. That is, despite the need to simultaneously service voice and data services, existing mobile communication systems support each service separately. Therefore, there is a demand for the implementation of a mobile communication system capable of supporting a voice service and at the same time a data service. Recently, a so-called 1xEV-DV (Evolution Data and Voice) system has been proposed as a mobile communication system.
The mobile communication system divides the entire service area into a plurality of cells, manages each of the base stations (BSs), and centrally controls these base stations with a mobile switching center (MSC). Mobile Station (MS) allows you to continue a call while moving from cell to cell. The base station communicates with the mobile terminal through a wireless channel.
Unlike land communication systems that communicate by wire, many transmission errors may occur due to effects such as fading and interference in mobile communication systems. The most widely used method of preventing such errors is to use a power high enough to cover fading, interference, and the like. On the other hand, excessively high power can interfere with other users' wireless channels. As such, power control on a wireless channel in a mobile communication system has an important effect on the performance of the system. Typically, a base station and a mobile terminal perform power control with each other. A series of procedures required for power control of a channel directed from a base station to a mobile terminal are called forward power control, and power control of a channel directed from the mobile terminal to the base station is performed. The sequence of steps required for this is called reverse power control.
Meanwhile, a CDMA system may simultaneously connect several code channels through one frequency channel at the same time. Using this feature, a mobile terminal in an overlapping area between base stations can simultaneously connect and communicate channels with two base stations for a single call, which is called a soft handoff. In this case, power control should be performed for all base stations communicating with the mobile terminal.

1 is a diagram illustrating channels related to reverse power control of a mobile terminal in soft handoff in a conventional mobile communication system. Herein, the mobile terminal 103 communicates with two base stations (sector, hereinafter referred to as "sector" in the case of a sector type base station), sector 1 101 and sector 2 102 by soft handoff. .

Referring to FIG. 1, the reverse power control procedure is described. Sector 1 (101) and Sector 2 (102) are measured on a reverse pilot channel (R-PICH) from a mobile 103. The signal-to-noise ratio (the ratio of noise power to pilot channel signal power, Ep / Nt) is compared with the outer loop set point set for outer loop power control. When the measured signal-to-noise ratio is greater than the reference value, the sectors 101 and 102 reduce the transmission power of the reverse channel to the terminal 103 by using a forward common power control channel (F-CPCCH). And vice versa to increase the transmit power. The indication is transmitted through a common power control channel (CPCCH) in the form of a power control bit (PCB).

The terminal 103 receives the PCB1 and the PCB2 from the sector 1 101 and the sector 2 102 through the CPCCH1 and the CPCCH2, respectively, and when any one of the PCB1 and the PCB2 instructs to lower the power of the reverse channel, Lowering the transmit power and increasing the reverse transmit power when both PCB1 and PCB2 instruct to power up.

Next, the forward power control procedure will be described. The transmission power of the forward channel is determined using channel quality information received through a reverse channel quality indicator channel (CQICH). The channel quality indication channel is the received signal strength, for example, carrier to interference ratio (C / I) value of the forward common pilot channel measured by the terminal for a particular sector. Used to transmit to the sector.

In general, the terminal measures carrier-to-interference ratio values of common pilot channels transmitted from neighboring sectors, and has a sector having the highest value among the measured values (hereinafter referred to as "best sector"). Forward channel quality information (for example, the measured carrier band interference ratio value) is transmitted to the optimal sector (sector 1 101 in FIG. 1) through a channel quality indication channel. The best sector then transmits forward packet data to the terminal.

In the prior art, the transmission power of the channel quality indication channel is maintained at a constant ratio with the reverse pilot channel and the reverse traffic channel. That is, when the transmission power of the reverse pilot channel and the traffic channel is lowered, the transmission power of the channel quality indication channel is also lowered by a predetermined ratio. When the transmission power of the reverse pilot channel and the traffic channel is increased, the transmission power of the channel quality indication channel is also determined. Increases in proportion.
However, unlike reverse pilot channels or traffic channels, channel quality indication channels are not subject to soft handoff. That is, the channel quality indication channel can be received only in one sector having the best forward channel quality among the sectors around the terminal. In contrast, the reverse pilot channel and the traffic channel are transmitted to two or more sectors in soft handoff, thereby ensuring good reception performance. In addition, in the case of traffic channels, reception performance can be improved through selective diversity or combining.
That is, when the power control of the channel quality indication channel is performed in the same way as the reverse pilot channel and the traffic channel, the desired reception performance can be obtained for the reverse pilot channel and the traffic channel, but the reception performance of the channel quality indication channel is It is likely to be lower than the desired level.

delete

In addition, in the case of the channel quality indication channel, the sector measures the received power for the channel quality indication channel, and if the received power does not have a level sufficient to ensure stable transmission, the channel quality indication channel is erased. When removed, the received signal of the channel quality indication channel is not decoded. Then, since the sector cannot acquire the forward channel quality information, the forward power control cannot be normally performed. In addition, in the mobile communication system performing forward packet data transmission with reference to forward channel quality information such as 1xEV-DV, if the channel quality indication channel is frequently removed, a problem occurs that the forward capacity is lowered. Therefore, there is a need for power control of the reverse channel to improve the channel quality indication channel performance.

delete

Accordingly, an object of the present invention is to provide a method and apparatus for controlling a transmission power of a reverse channel quality indicator channel (CQICH) for transmitting channel quality information of a forward channel in a mobile communication system.

Another object of the present invention is to provide a method and apparatus for adjusting a power ratio to a pilot of a reverse channel quality indication channel in a mobile communication system.
Another object of the present invention is to provide a method and apparatus for adjusting a power ratio to a pilot of a channel quality indication channel according to an erasure rate of a reverse channel quality indication channel in a mobile communication system.

In accordance with an aspect of the present invention, a base station apparatus includes a base station transmitting power control bits for power control of reverse channels and a terminal controlling transmission power of reverse channels according to the power control bits. In the mobile communication system, the base station performs the power control of the reverse channel quality indication channel received from the terminal,
A cancellation detector for determining whether to cancel by measuring the received power of the reverse channel quality indication channel every time slot, a removal rate calculator for accumulating and storing the removal determination result for a predetermined N slots, and calculating a removal rate during the N slots; And a control bit generator for determining a power ratio control bit transmitted to the terminal according to the removal rate in order to indicate an increase or decrease in power ratio relative to the reverse pilot of the channel quality indication channel.
A base station method according to an embodiment of the present invention for achieving the above object, for performing the power control of the reverse channel quality indication channel in the base station receiving a reverse pilot channel, a reverse traffic channel and a reverse channel quality indication channel from a terminal. In the method,
Measuring a received power of the reverse pilot channel to generate a power control bit for indicating an increase or decrease of the transmit power of the reverse channels; and determining whether to remove the measured power by measuring the received power of the reverse channel quality indication channel. Calculating a removal rate for a predetermined N slot according to the removal determination result, determining a power ratio control bit for indicating an increase or decrease in power ratio relative to a reverse pilot of the channel quality indication channel according to the removal rate; Transmitting the power ratio control bit in at least one selected timeslot of a plurality of timeslots on a forward channel, and transmitting the power control bit in remaining timeslots except the at least one selected timeslot. It features.

Terminal device according to an embodiment of the present invention for achieving the above object The terminal device according to an embodiment of the present invention for achieving the above object, to transmit the reverse pilot channel, reverse traffic channel and reverse channel quality indication channel to the base station An apparatus for performing power control of the reverse channels in a terminal, the apparatus comprising:
Receiving a control bit from the base station every time slot, and whether the received control bit is a power ratio control bit indicating an increase or decrease in power ratio relative to a reverse pilot of the channel quality indication channel or an increase in transmit power of the reverse channels or A control bit detector for determining whether a power control bit indicates a reduction; a power ratio controller for controlling a power ratio relative to a reverse pilot of the channel quality indication channel according to the power ratio control bit, if the control bit is a power ratio control bit; If the bit is a power ratio control bit, the power ratio is provided from the power ratio controller. If the control bit is a power control bit, the reverse pilot channel, the reverse traffic channel, and the reverse channel quality indication channel according to the power control bit and the provided power ratio. Transfer gains of And a gain controller for controlling.
A terminal method according to an embodiment of the present invention for achieving the above object, in the method for performing the power control of the reverse channel in the terminal transmitting a reverse pilot channel, a reverse traffic channel and a reverse channel quality indication channel to a base station; ,
Receiving a power ratio control bit indicative of an increase or decrease in power ratio relative to a reverse pilot of the channel quality indication channel in at least one selected timeslot of a plurality of timeslots on a forward channel, and according to the power ratio control bit Controlling a power ratio to a reverse pilot of a quality indication channel, receiving a power control bit indicating an increase or decrease in transmit power of the reverse pilot channels in the remaining time slots except for the at least one selected time slot; And controlling the transmission gain of the reverse pilot channel, the reverse traffic channel, and the reverse channel quality indication channel according to the power control bit and the controlled power ratio.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be noted that reference numerals and like elements among the drawings are denoted by the same reference numerals and symbols as much as possible even though they are shown in different drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In the following description, a channel quality indicator channel (CQICH) is a forward measurement measured by a terminal on a forward common pilot channel transmitted from neighboring base stations (sectors in the case of a sector type base station). Channel quality, i.e., signal strength (e.g., carrier-to-interference ratio, C / I). Channel Quality Indication Another information carried on the channel is a sector indicator indicating a sector having the best forward channel quality, that is, a best sector. The sector indicator is used to select a sector from which a terminal wishes to receive packet data over a forward traffic channel. The sector that receives the forward channel quality information and the sector indicator through the channel quality indication channel determines the transmission time, modulation method, code rate, etc. of the forward packet data using the information. . The sector also schedules packet transmissions using the forward channel quality information.
2 illustrates a receiver structure of a channel quality indication channel in a typical mobile communication system.
Referring to FIG. 2, a pseudo-random noise code (PN) despreader 201 despreads a signal received through a wireless channel with a predetermined PN code assigned to a receiver. A Walsh code despreader 202 despreads the PN despread signal from the PN despreader 201 with a predetermined Walsh code assigned to a channel quality indication channel. The channel compensator 203 compensates for the difference in transmission power between the pilot channel and the channel quality indication channel by multiplying the Walsh despread signal from the Walsh despreader 202 by the conjugate signal of the channel estimation signal obtained from the pilot channel. do.
Meanwhile, the erasure detector 204 measures the reception power of the channel compensated signal from the channel compensator 203, and compares the measured reception power with a predetermined reference power to determine whether the erasure is performed. do. The determination of whether to remove the channel quality indication is to determine whether the channel has enough energy to obtain a constant reception performance. If the measured received power does not reach the reference power, the removal detector 204 disables the decoder 205. Otherwise, the cancellation detector 204 enables the decoder 205, whereby the decoder 205 decodes the channel compensated signal to restore forward channel quality information. The recovered channel quality information is used for scheduling of forward packet transmission.

As mentioned above, if the power control of the channel quality indication channel is performed in the same way as the reverse pilot channel or the traffic channel, the received power of the channel quality indication channel received from the terminal in soft handoff is less than that in the soft handoff. Will be low. This is a problem caused by performing power control in the same way as other reverse channels that can be transmitted to several sectors even though the channel quality indication channel is transmitted only in one sector.

In order to solve the above problem, the present invention observes an erasure rate for the channel quality indication channel and adjusts the ratio of the transmit power of the channel quality indication channel to the pilot channel based on this. To this end, the base station transmits a command for controlling the power ratio to the pilot of the channel quality indication channel. Then, the terminal adjusts the power ratio of the channel quality indication channel to the reverse pilot channel (PICH) in response to the command.
The CQICH Traffic to Pilot Ratio Control Bit (RCB) is used to control the power of the entire reverse channel. As distinguished from a power control bit (PCB) transmitted through a forward channel, the power control bit is transmitted by puncturing. The power control bit PCB and the power ratio control bit RCB may be transmitted through a forward common power control channel (F-CPCCH) or another forward channel, but for convenience of description, the control bits are transmitted through a forward common power control channel. Will be done.

3 is a diagram illustrating transmission of a power control bit (PCB) and a power ratio control bit (RCB) for controlling a power ratio to a pilot of channel quality indication channel traffic in a mobile communication system according to an embodiment of the present invention. The figure shows an example.

In the illustrated example, the power ratio control bit RCB transmitted on the forward common power control channel (F-CPCCH) is transmitted occupying one slot having a length of 1.25 ms and its transmission period is 16 slots. That is, the base station transmits a power ratio control bit (RCB) for controlling the power ratio of the channel quality indication channel and the reverse pilot channel instead of the power control bit PCB for the reverse power control every 16 slots. The terminal increases or decreases the power ratio relative to the reverse pilot of the channel quality indication channel according to the power ratio control bit RCB. Here, the increased or decreased size is to be notified from the base station to the terminal or set in advance by signaling when the base station initiates communication with the terminal.
For example, if the power ratio control bit is 'increase (+)', the terminal increases the power ratio of the channel quality indication channel and the pilot channel by 1dB. On the contrary, if the power ratio control bit is 'minus', the terminal reduces the power ratio of the channel quality indication channel and the pilot channel by 1 dB.

In addition, in FIG. 3, the terminal and the base station have a common knowledge of the transmission cycle and the position of the slot in which the base station transmits a power ratio control bit (RCB). The transmission period and the position within the period may be notified from the base station to the terminal by using a signaling message or may be set in advance in the terminal and the base station after it is determined in the optimization process when installing the mobile communication system. As another example, the transmission period and the position within the period may be determined using parameters commonly known by the base station and the terminal, such as a long code mask of the terminal.

4 illustrates a procedure for a base station to transmit a power control bit (PCB) and a power ratio control bit (RCB) in a mobile communication system according to an embodiment of the present invention. The operation shown below is performed in every slot of the reverse channel at the base station.

Referring to FIG. 4, in step 401, the base station receives signals of a channel quality indicator channel (CQICH) and a reverse pilot channel (R-PICH) transmitted by the terminal in the reverse direction. In step 402, the base station measures the received power for the reverse pilot channel and the channel quality indication channel (CQICH), and removes the channel quality indication channel by using the received power of the measured channel quality indication channel. Determine whether or not.
In more detail with reference to step 402, the base station determines that the received power of the channel quality indication channel is removed if it does not reach a predetermined predetermined reference power. The determination result is accumulated and stored for a window of a predetermined time. For example, when the size of the window is N slots, a channel quality indication channel removal decision result (for example, the number of removals) of recent N slots is accumulated and stored. That is, if the reception power of the channel quality indication channel is less than the reference power, the base station increases the number of removals during the recent N slots by '1'.

In step 403, the base station determines whether the current slot is a time interval for transmitting a power ratio control bit. As described above, the base station already knows in which slot the power ratio control bit should be transmitted, that is, the transmission period of the power ratio control bit and the position of the slot for transmitting the power ratio control bit within the transmission period. If it is determined in step 403 that the current slot is a time interval for transmitting the power ratio control bit, in step 404, the base station calculates a CQICH erasure rate of the terminal for the current slot. The CQICH removal rate is calculated as in Equation 1 below.

delete

In Equation 1, "N" is a window size for calculating a CQICH removal rate.

In step 405, the base station determines whether to increase or decrease the power ratio to the pilot of the channel quality indication channel by using the CQICH removal rate. If the CQICH removal rate is greater than a predetermined predetermined reference removal rate, a power ratio control bit (referred to as "RCB (+)") is generated to indicate an increase in the power ratio to the pilot of the channel quality indication channel in step 406, and the CQICH removal rate is generated. If not greater than the reference rejection rate, a power ratio control bit (referred to as " RCB (−) ") is generated that indicates at 407 to reduce the power ratio relative to the pilot of the channel quality indication channel.

On the other hand, if it is determined in step 403 that it is not the time interval to transmit the power ratio control bit RCB, the flow proceeds to step 408 to generate a power control bit PCB for power control of the reverse channels. In more detail with reference to step 408, if the reception power of the pilot channel measured in step 402 is not greater than a predetermined reference power, a power control bit ("PCB (+)) indicating to increase the transmission power of the reverse channel Is generated, and a power control bit (referred to as " PCB (−) ") is generated which instructs to reduce the transmit power of the reverse channel if it is larger than the reference power.
In step 409, the control bit generated in step 406 or step 407 or step 408 is transmitted through the forward common power control channel (F-CPCCH).

5 illustrates a procedure for a terminal to receive a power ratio control bit RCB in a mobile communication system according to an embodiment of the present invention. The operation shown below is performed in every slot of the forward channel in the terminal.

Referring to FIG. 5, in step 501, a terminal receives a signal of a common power control channel (CPCCH) from a signal transmitted from a base station in a forward direction, and detects a control bit from the received signal. According to an embodiment of the present invention, the common power control channel is transferred not only a power control bit PCB but also a power ratio control bit RCB for controlling a power ratio to a pilot of a channel quality indication channel. Therefore, in step 502, the terminal determines whether the current slot is a time interval for receiving the power ratio control bit to determine whether the detected control bit is a power control bit or a power ratio control bit. As described above, the terminal already knows in which slot the base station transmits the power ratio control bit, that is, the transmission period of the power ratio control bit and the position of the slot for transmitting the power ratio control bit within the transmission period.

If it is determined in step 502 that the time interval to receive the power ratio control bit, the terminal determines that the detected control bit is the power ratio control bit and performs steps 503 to 505 to control the power ratio to the pilot of the channel quality indication channel. do.
In more detail, in step 503, the terminal checks whether the number of sectors included in an active set is greater than 1, in order to confirm whether the terminal is currently communicating with one or more base stations by soft handoff. do. As is known, the active set means a list of sectors with which the terminal communicates. If one or more sectors are included in the active set, it can be determined that the terminal is performing a soft handoff.
If the number of sectors included in the active set is only one as a result of the inspection, in step 504, the terminal controls the power ratio to the pilot of the channel quality indication channel using the power ratio control bit. That is, if the power ratio control bit means an increase, the power ratio is increased. If the power ratio control bit means a decrease, the power ratio is decreased.
On the other hand, if the number of sectors included in the active set is two or more, in step 505, the terminal receives the power ratio control bits from the sectors in the active set. Accordingly, the terminal controls the power ratio to the pilot of the channel quality indication channel according to the sector to receive forward packet data among the sectors included in the active set, that is, the power ratio control bit from the optimal sector. That is, if the power ratio control bit from the optimal sector means a decrease, the power ratio is decreased, and if it means an increase, the power ratio is increased.

On the other hand, if it is determined in step 502 that it is not a time interval for receiving the power ratio control bit, the terminal determines that the detected control bit is a power control bit, and proceeds to step 506 and performs a reverse link according to the power control bit. Control the transmit power of
In more detail with reference to step 506, if the power control bit is increased, the gain of the reverse pilot channel and the reverse traffic channel is increased by a predetermined amount, and the gain of the channel quality indication channel is increased according to the power ratio of the pilot of the channel quality indication channel. Adjust On the other hand, if the power control bit is reduced, the gain of the reverse pilot channel and the reverse traffic channel is reduced by a predetermined amount, and the gain of the channel quality indication channel is adjusted according to the power ratio of the pilot of the channel quality indication channel. Here, the power ratio to the pilot of the channel quality indication channel is controlled by the power ratio control bit received from the base station at predetermined intervals as shown in steps 503 to 505.

On the other hand, in the time interval when the power ratio control bit is received instead of the power control bit, the terminal changes the channel gain of the channel quality indication channel according to the power ratio control bit, but for the other reverse channels according to the power control bit received in the previous slot. Keep the gain as it is. That is, in this time period, only the transmission power of the channel quality indication channel changes.

6 illustrates a receiver structure of a base station for controlling a power ratio to a pilot of a channel quality indication channel in a mobile communication system according to an embodiment of the present invention.

Referring to FIG. 6, the PN despreader 601 multiplies a signal received through a wireless channel in a time slot and outputs a predetermined PN code. The Walsh Despreader 602a multiplies the signal from the PN Despreader 601 by a predetermined Walsh code assigned to the channel quality indication channel H. The channel compensator 603 compensates the transmission power difference between the pilot channel and the channel quality indication channel by multiplying the signal from the Walsh inverse spreader 602a by the conjugate signal of the channel estimation signal obtained from the pilot channel.
The erasure detector 604 measures the received power of the channel compensated signal and compares the measured received power with a predetermined reference value to determine whether the channel quality indication channel is removed. The determination of whether to remove or not is determined by whether the received power of the channel quality indication channel exceeds the reference value. The elimination determined by the elimination detector 604 is input to an erasure rate calculator 605.
As shown in Equation 1, the removal rate controller 605 counts the number of removal determinations for a given window size N slot, and calculates the removal rate by dividing the ratio of the number of removal determinations by N. The calculated removal rate is provided to a control bit generator 607.

On the other hand, the Walsh despreader 602b multiplies the signal from the PN despreader 601 by a predetermined Walsh code assigned to the reverse pilot channel. A power measurer 606 measures the received power of the signal from the Walsh despreader 602b and provides it to the control bit generator 607.
The control bit generator 607 determines whether or not the current time slot is a time interval for transmitting the power ratio control bit RCB for each time slot. This may be determined by a system parameter preset between the base station and the terminal. If the current time slot is a time interval for transmitting the power ratio control bit RCB, the control bit generator 607 generates the power ratio control bit RCB by comparing the removal rate provided from the removal rate calculator 605 with a predetermined reference removal rate. That is, if the removal rate is greater than the reference removal rate, the power ratio control bit RCB (+) means an increase, and when the removal rate is smaller than or equal to, the power ratio control bit RCB (−) means a decrease.
On the other hand, if the current time slot is not a time interval to transmit the power ratio control bit RCB, the control bit generator 607 generates a power control bit PCB by comparing the received power provided from the power meter 606 with a predetermined reference power. That is, if the received power is greater than the reference power, a power control bit PCB (-) is generated, which means a decrease, and if it is less than or equal to, a power control bit PCB (+) is created, which means an increase.
The control bits generated by the control bit generator 607, that is, the power control bit PCB or the power ratio control bit RCB are transmitted to the terminal through the forward common power control channel.

7 illustrates a receiver structure of a terminal for controlling the transmission power of a reverse channel in a mobile communication system according to an embodiment of the present invention.

Referring to FIG. 7, the PN despreader 701 multiplies a signal received through a wireless channel every time slot and outputs a predetermined PN code. The Walsh despreader 702 multiplies the signal from the PN despreader 701 by a predetermined Walsh code assigned to the common power control channel. The channel compensator 703 multiplies the signal from the Walsh inverse spreader 702 by the conjugate signal for channel compensation.
The control bit detector 704 determines whether the signal from the channel compensator 703 is a power control bit PCB or a power ratio control bit RCB. That is, the control bit detector 704 may determine whether the current slot is a time interval for receiving the power ratio control bit RCB to determine whether the signal from the channel compensator 703 is a power control bit PCB or a power ratio control bit RCB.
If the current slot is a time interval for receiving the power ratio control bit RCB, the control bit detector 704 detects the power ratio control bit RCB from the signal from the channel compensator 703 and provides the power ratio control bit RCB to the ratio controller 705. Then, the power ratio controller 705 determines the power ratio to the pilot of the channel quality indication channel according to the power ratio control bit RCB and provides it to the gain controller 706.
On the other hand, if the current slot is not the time interval for receiving the power ratio control bit RCB, the control bit detector 704 detects the power control bit PCB in the signal from the channel compensator 703 and provides it to the gain controller 706. The gain controller 706 then determines and outputs transmission power of reverse channels according to the power control bit PCB. That is, if the power control bit PCB increases, the transmit power of the reverse pilot channel and the reverse traffic channel is increased by a predetermined amount, and if the decrease means the transmit power of the reverse pilot channel and the reverse traffic channel is reduced by the predetermined amount. At this time, the transmission power of the channel quality indication channel is increased or decreased according to the power ratio to the pilot provided from the power ratio controller 705.
As such, when the power ratio of the channel quality indication channel to the pilot of the channel quality indication channel is controlled according to the removal rate of the channel quality indication channel, the channel quality of the channel quality indication channel is improved even when the quality of the other reverse channels is good and the channel quality indication channel is poor. Can be improved. In other words, when the quality of the other reverse channels is good, but the removal occurs frequently in the channel quality indication channel, the power control bit transmitted from the base station to the terminal indicates a decrease and the power ratio control bit indicates an increase. Then, even if the transmission power of all reverse channels is reduced by the power control bit PCB in the terminal, the transmission power of the channel quality indication channel is reduced at a smaller rate. This is because the power ratio to the pilot of the channel quality indication channel is increased by the power ratio control bit. Therefore, the channel quality indication channel can be maintained relatively good.

FIG. 8 illustrates an operation in which one base station distributes power ratio control bits for a plurality of terminals by time slots.

In FIG. 8, it is assumed that the transmission period of the power ratio control bit for each of the plurality of terminals MS1, MS2, MS3, and MS4 is 16 slots. As shown, the base station transmits a power ratio control bit in a different slot for each terminal. The transmission of the power ratio control bits as described above is to distribute the increase and decrease of the amount of backward interference generated by changing the power ratio to the pilot of the channel quality indication channel. There are many ways to distribute the transmission of power ratio control bits.

One example is the use of signaling. That is, the base station determines how to distribute the power ratio control bits and then informs each terminal of the location of the slot for transmitting the corresponding power ratio control bits through signaling.

 Another example is to use a parameter that is uniquely assigned to each mobile terminal. For example, by applying a reverse frame offset (RFO) uniquely assigned to call establishment for each terminal to Equation 2, it is possible to determine whether to transmit a power ratio control bit for every time slot. .

In Equation 2, T is a system time of a slot unit, and since the terminal and the base station are synchronized, the same system time is used. When the above Equation 2 becomes 0, the terminal and the base station determine the transmission time of the power ratio control bit. As described above, the method using the unique parameter must be known in advance by the terminal and the base station, and must be determined to control the power ratio to the reverse pilot of the channel quality indication channel.

9 illustrates an operation of repeatedly transmitting the same power ratio control bits according to an embodiment of the present invention.

As shown, the base station repeatedly transmits the same power ratio control bit four times during the transmission period of 16 slots of the power ratio control bit. As described above, the repeated transmission of the power ratio control bit every 4 slots is to transmit the control command of the power ratio to the pilot of the channel quality indication channel within the period as accurately as possible. If the same power ratio control bit is repeatedly transmitted, the terminal can obtain more improved reception performance.

As described above, the present invention is to maintain a constant reception performance of the channel when the terminal supports the channel during soft handoff in the mobile communication system. The present invention has been proposed for the problem that the reception power of the channel quality indication channel is reduced during soft handoff, but can be applied to improve the reception performance of the channel quality indication channel even for a terminal that is not in soft handoff.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

As described above, the present invention provides a technique for controlling the power ratio of the pilot of the reverse channel quality indication channel to which the soft handoff is not particularly applied in the mobile communication system, the reverse channel quality indication channel for transmitting the forward channel state information It has the effect of guaranteeing a constant reception performance at the receiving side. Therefore, the reliability of power control of the reverse channel quality indication channel can be improved more, and the accurate forward channel quality information can be received at the base station, thereby improving the call quality.

Claims (39)

delete delete delete delete delete delete delete delete delete delete delete In a mobile communication system comprising a base station transmitting a power control bit for power control of the reverse channel and a terminal for controlling the transmission power of the reverse channel according to the power control bit, the reverse channel quality indication that the base station is received from the terminal An apparatus for performing power control of a channel, A cancellation detector for measuring the received power of the reverse channel quality indication channel every time slot to determine whether to cancel or not; A removal rate calculator which accumulates and stores the removal determination result for a predetermined N slot, and calculates a removal rate during the N slot; And a control bit generator configured to determine, according to the removal rate, a power ratio control bit transmitted to the terminal to indicate an increase or decrease of a power ratio with respect to a reverse pilot of the channel quality indication channel. The method of claim 12, wherein the removal rate, Wherein the ratio is calculated as the ratio of the number of times determined to be removed during the N slots for the N. The method of claim 12, wherein the control bit generator, And determining the power ratio control bit to indicate an increase when the removal rate is equal to or greater than a predetermined reference removal rate, and determining the power ratio control bit to indicate a decrease when the removal rate is equal to or less than the predetermined reference removal rate. The method of claim 14, wherein the power ratio control bit, Reverse channel power control apparatus characterized in that the transmission between the base station and the terminal in a predetermined time slot in a predetermined period. The method of claim 15, wherein the power ratio control bit, Reverse channel power control device characterized in that the transmission in place of the power control bit in a predetermined transmission interval. The method of claim 12, wherein the power ratio control bit, Reverse channel power control apparatus characterized in that the transmission is distributed by time zones so as not to overlap with the power ratio control bits for the other terminals that are communicating with the base station. The method of claim 17, wherein the power ratio control bit, Reverse channel power control apparatus characterized in that the transmission in the timeslot satisfying the following equation (3).

Here, T is a system time in a slot unit, INT is a period in which the power ratio control bit is transmitted, and X is a parameter uniquely allocated to a terminal. The method of claim 12, wherein the power ratio control bit, And at least two repetitive transmissions in time slots promised between the base station and the terminal every predetermined period. An apparatus for performing power control of the reverse channels in a terminal transmitting a reverse pilot channel, a reverse traffic channel, and a reverse channel quality indication channel to a base station, the apparatus comprising: Receiving a control bit from the base station every time slot, and whether the received control bit is a power ratio control bit indicating an increase or decrease in power ratio relative to a reverse pilot of the channel quality indication channel or an increase in transmit power of the reverse channels or A control bit detector for determining whether the power control bit indicates a reduction; A power ratio controller for controlling a power ratio to a reverse pilot of the channel quality indication channel according to the power ratio control bit if the control bit is a power ratio control bit; If the control bit is a power ratio control bit, the power ratio is provided from the power ratio controller. If the control bit is a power control bit, the reverse pilot channel, the reverse traffic channel, and the reverse channel quality according to the power control bit and the provided power ratio. And a gain controller for controlling the transmission gains of the indication channel. The method of claim 20, wherein the control bit detector, In each time slot, it is determined whether the time slot is a predetermined time slot to transmit a power ratio control bit between the terminal and the base station. If the time slot is a predetermined time slot, the control bit is determined to be a power ratio control bit. Reverse channel power control, characterized in that the determination. The method of claim 20, wherein the power controller, Determine a transmission power of the reverse pilot channel and the reverse traffic channel according to the power control bit, and determine a transmission power of the reverse channel quality indication channel according to the determined transmission power and the provided power ratio. Power controller. The method of claim 20, wherein the power ratio control bit, And a base station having a maximum reception power among a plurality of base stations in an active set connecting communication with the terminal. In a mobile communication system comprising a base station transmitting a power control bit for power control of the reverse channel and a terminal for controlling the transmission power of the reverse channel according to the power control bit, the reverse channel quality indication that the base station is received from the terminal In the method for performing power control of the channel, Determining whether or not the signal is removed by measuring the received power of the reverse channel quality indication channel every time slot; Accumulating and storing the removal determination result for a predetermined N slot, and calculating a removal rate for the N slot; Determining a power ratio control bit indicative of an increase or decrease in power ratio relative to a reverse pilot of the channel quality indication channel according to the calculated removal rate; And transmitting the determined power ratio control bit to the terminal. The method of claim 24, wherein the removal rate, And calculates the ratio of the number of times determined to be eliminated during the N slots relative to the N. The method of claim 24, wherein the determining is, And determining the power ratio control bit to indicate an increase when the removal rate is equal to or greater than a predetermined reference removal rate, and determining the power ratio control bit to indicate a decrease when the removal rate is equal to or less than the predetermined reference removal rate. The method of claim 26, wherein the transmitting step, And transmitting the power ratio control bit at a predetermined period in a time slot previously agreed between the base station and the terminal. The method of claim 27, wherein the transmitting step, And transmitting the power ratio control bit in place of the power control bit in the transmission section of the power control bit. The method of claim 24, wherein the transmitting step, And transmitting the power ratio control bits in a timely manner so as not to overlap with the power ratio control bits for other terminals connecting to the base station. The method of claim 29, wherein the transmitting step, And transmitting the power ratio control bit in a timeslot satisfying Equation 4 below.

Here, T is a system time in a slot unit, INT is a period in which the power ratio control bit is transmitted, and X is a parameter uniquely allocated to a terminal. The method of claim 24, wherein the transmitting step, And transmitting the power ratio control bit at least twice in timeslots promised between the base station and the terminal. A method for performing power control of the reverse channel quality indication channel at a base station receiving a reverse pilot channel, a reverse traffic channel and a reverse channel quality indication channel from a terminal, Measuring a received power of the reverse pilot channel to generate a power control bit for indicating an increase or decrease in transmit power of the reverse channels; Determining whether to cancel by measuring the received power of the reverse channel quality indication channel, and calculating a removal rate during a predetermined N slot according to the removal determination result; Determining a power ratio control bit according to the removal rate to indicate an increase or decrease of a power ratio with respect to a reverse pilot of the channel quality indication channel; Transmitting the power ratio control bit in at least one selected timeslot of a plurality of timeslots on a forward channel, and transmitting the power control bit in remaining timeslots except the at least one selected timeslot. Reverse channel power control method characterized in that. The method of claim 32, wherein the power ratio control bit, And if the removal rate is greater than or equal to a predetermined reference removal rate, determining to indicate an increase, and if the removal rate is less than or equal to the reference removal rate, determining a decrease. A method for performing power control of the reverse channels in a terminal transmitting a reverse pilot channel, a reverse traffic channel, and a reverse channel quality indication channel to a base station, the method comprising: Receives a control bit from the base station every time slot, and whether the received control bit is a power ratio control bit indicating an increase or decrease in power ratio relative to a reverse pilot of the channel quality indication channel or an increase in transmit power of the reverse pilot channels. Or determining whether the power control bit indicates a reduction; If the control bit is a power ratio control bit, controlling a power ratio with respect to a reverse pilot of the channel quality indication channel according to the power ratio control bit; If the control bit is a power control bit, controlling the transmission gain of the reverse pilot channel, the reverse traffic channel, and the reverse channel quality indication channel according to the power ratio controlled in the power control bit and the previous time slot. Reverse channel power control method characterized in that. The method of claim 34, wherein the determining is, In each time slot, it is determined whether the time slot is a predetermined time slot to transmit a power ratio control bit between the terminal and the base station. If the time slot is a predetermined time slot, the control bit is determined to be a power ratio control bit. Reverse channel power control method characterized in that it is determined. 35. The method of claim 34, wherein controlling the transmission gain of the reverse channels comprises: Determine a transmission power of the reverse pilot channel and the reverse traffic channel according to the power control bit, and determine a transmission power of the reverse channel quality indication channel according to the determined transmission power and the provided power ratio. Power control method. The method of claim 34, wherein the power ratio control bit, And receiving from a base station having a maximum reception power among a plurality of base stations in an active set connecting communication with the terminal. A method for performing power control of the reverse channels in a terminal transmitting a reverse pilot channel, a reverse traffic channel, and a reverse channel quality indication channel to a base station, the method comprising: Receiving a power ratio control bit indicative of an increase or decrease in power ratio relative to a reverse pilot of the channel quality indication channel in at least one selected timeslot of a plurality of timeslots on a forward channel; Controlling a power ratio to a reverse pilot of the channel quality indication channel according to the power ratio control bit; Receiving a power control bit indicating an increase or decrease in transmit power of the reverse pilot channels in the remaining time slots except for the at least one selected time slot; And controlling transmission gains of the reverse pilot channel, the reverse traffic channel, and the reverse channel quality indication channel according to the power control bit and the controlled power ratio. The method of claim 38, wherein the power ratio control ratio, And receiving from a base station having a maximum reception power among a plurality of base stations in an active set connecting communication with the terminal.

Images